1. Field of the Invention
The present invention relates to a thermal expansion suppressing member and an anti-thermally-expansive member, and more particularly, to a novel anti-thermally-expansive member, including an oxide having negative thermal expansion properties which is joined to a metal.
2. Description of the Related Art
In general, an electronic member, an optical member, and a structural member are made of materials such as metal, resin, ceramic, and glass. These conventional materials expand or contract depending upon an increase or decrease in environmental temperature due to their positive thermal expansion properties.
For example, in a conventional metal-based heat radiation plate (heat sink), metal members mainly containing aluminum and copper having good thermal conduction have been widely used. These metal members have thermal expansion largely different from those of members such as an insulator, a semiconductor, and a solder to be cooled, and hence, there is a problem in that the metal members have adverse effects caused by thermal stress strain.
In order to solve such problem, the use of a metal oxide having negative thermal expansion properties has been proposed.
For example, Japanese Patent Application Laid-Open No. H10-096827 discloses an optical fiber element in which thermal expansion is suppressed using ZrW2O8 having a linear expansion coefficient in the range of −4.7×10−6/K to −9.4×10−6/K. However, there is a problem in that a negative thermal expansion material of a tungstate-based metal oxide still has a small absolute value of a linear expansion coefficient.
PCT Publication WO06-011590A discloses a material including a manganese nitride as a main component to increase a negative linear expansion coefficient to −60×10−6/K at largest. However, there are problems in that such negative thermal expansion material including a manganese nitride exhibits negative thermal expansion properties in a narrow temperature region, and in that the material having a larger absolute value of a linear expansion coefficient exhibits negative thermal expansion properties in lower temperature regions compared with a practical temperature region.
The present invention has been achieved in order to solve the above-mentioned problems. An object of the present invention is to provide a Bi-based thermal expansion suppressing member having negative thermal expansion properties and an anti-thermally-expansive member including the thermal expansion suppressing member joined to a metal.